Recently, BD media have been released as removable recording media that can be used for recording high definition movies. The recording format for BD media has been standardized in System Description Blu-ray Disc Rewritable Format Version 2.0 (hereinafter referred to as “BDRE 2.0 standard”) by BDA (Blu-ray Disc Association).
The BDRE 2.0 standard allows HD quality recording of digital broadcasts without degradation. According to the BDRE 2.0 standard, a plurality of management information files are used for managing AV stream files. The management information files are used for managing, as separate files, the count of broadcast programs (hereinafter referred to as “PLAYLIST”), a list of playback sections (hereinafter referred to as “PLAYITEMS”) of an AV stream file, and an entry point map (hereinafter referred to as “EPMAP”) used for random accesses to the AV stream.
The upper limits of the count of the PLAYLISTs and the count of the PLAYITEMs recordable on a BD medium are defined in the standard (The data structure according to the BDRE 2.0 standard will be described later).
At data recording or data editing in conformity with the BDRE standard, the count of PLAYLISTs and the count of PLAYITEMs, which are managed as separate files of the management information, are not allowed to exceed their upper limits. Thus recording/editing apparatuses have to read all the management information files before the recording or the editing of AV streams, to confirm that the counts do not exceed their upper limits. Such pre-processing procedure before the recording/editing requires a long time (up to 1 to 2 minutes).
In view of the above, Patent Literature 1 discloses a conventional art for reducing the time required for reading data recorded on a recording/playback medium. According to this art, part of the management information used for recording and playback is saved from the recording/playback medium to a built-in backup memory of the apparatus. When the apparatus is powered on (i.e. “PON”) or a recording/playback medium is inserted into the apparatus, if required information exists in the backup memory, the apparatus uses the information in the backup memory. This method increases the speed of reading of the management information.
Patent Literature 1: Japanese Patent Application Publication No. 08-249863